Prevention of Hydrogen Embrittlement of High Strength Alloy Steel using Surface Coating Techniques

High strength steel has being used for various engineering & industrial applications. Industries like Automobile, Aerospace, Power & Energy, Oil, Marine, Defence etc., were using high strength steel to develop new light weight energy efficient solutions with an improved efficiency and lower the overall weight of the structure. High strength steels are subjected to a perennial problem of hydrogen embrittlement during the course of manufacturing and under a specific condition of the operation resulting in an unexpected failure of components below the permissible stress limit and without any prior warning severely amputating the service life. This failure is predominantly brittle in nature & results in catastrophic accident. Seriousness of the issue demands a systematic analysis of parameters responsible for hydrogen embrittlement by simulating the failure in a controlled environment using several laboratory tests. EN24 steel, which is an alloy steel having nickel, chromium & molybdenum as main alloying elements offers good machinability and claims a high strength with the fine resilience, hardness and wear resistance. EN24 steel is primarily used in automotive, machine tool and power generating equipment industries for manufacturing of frames, structural members, fasteners, power transmission shafts, axles, landing gears and etc. This paper mainly focuses on evaluating the performance of various industrial coatings being used in industries for the protection from hydrogen embrittlement. Specimen of EN24 high strength steel specimen were subjected to external hydrogen embrittlement by cathodic pre-charging of specimen in an acidic environment and testing the coated and bare specimen using conventional as well as slow strain rate test technique. This study aims to find out the suitable coatings to mitigate the hydrogen embrittlement of high strength steel. As high strength steel is widely used for manufacturing of fasteners and various critical load taking members the failure due to hydrogen embrittlement could be catastrophic. By use of the suitable coatings on the surface of components one can produce a barrier layer between object and surrounding atmosphere to protect the direct exposure to any electrolytic reaction that resulting in hydrogen embrittlement. The objective of this research work is to evaluate the performance of various coatings to prevent the hydrogen embrittlement.